Parasitic peptides! The structure and function of neuropeptides in parasitic worms

Parasitic worms come from two very different phyla-Platyhelminthes (flatwor ms) and Nematoda (roundworms). Although both phyla possess nervous systems with highly developed peptidergic components. there are key differences in the structure and action of native neuropeptides in the two groups. For exa mple, the most abundant neuropeptide known in platyhelminths is the pancrea tic polypeptide-like neuropeptide F, whereas the most prevalent neuropeptid es in nematodes an FMRFamide-related peptides (FaRPs), which are also prese nt in platyhelminths. With respect to neuropeptide diversity, platyhelminth species possess only one or two distinct FaRPs, whereas nematodes have upw ards of 50 unique FaRPs. FaRP bioactivity in platyhelminths appears to be r estricted to myoexcitation, whereas both excitatory and inhibitory effects have been reported in nematodes. Recently interest has focused on the pepti dergic signaling systems of both phyla because elucidation of these systems will do much to clarify the basic biology of the worms and because the pep tidergic systems hold the promise of yielding novel targets for a new gener ation of antiparasitic drugs. (C) 1999 Elsevier Science Inc. All rights res erved.